Moure VR, Costa FF, Cruz LM, Pedrosa FO, Souza EM, Li XD, Winkler F, Huergo LF. Regulation of nitrogenase by reversible mono-ADP-ribosylation.
Curr Top Microbiol Immunol 2015;
384:89-106. [PMID:
24934999 DOI:
10.1007/82_2014_380]
[Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Posttranslational modification of proteins plays a key role in the regulation of a plethora of metabolic functions. Protein modification by mono-ADP-ribosylation was first described as a mechanism of action of bacterial toxins. Since these pioneering studies, the number of pathways regulated by ADP-ribosylation in organisms from all domains of life expanded significantly. However, in only a few cases the full regulatory ADP-ribosylation circuit is known. Here, we review the system where mono-ADP-ribosylation regulates the activity of an enzyme: the regulation of nitrogenase in bacteria. When the nitrogenase product, ammonium, becomes available, the ADP-ribosyltransferase (DraT) covalently links an ADP-ribose moiety to a specific arginine residue on nitrogenase switching-off nitrogenase activity. After ammonium exhaustion, the ADP-ribosylhydrolase (DraG) removes the modifying group, restoring nitrogenase activity. DraT and DraG activities are reversibly regulated through interaction with PII signaling proteins . Bioinformatics analysis showed that DraT homologs are restricted to a few nitrogen-fixing bacteria while DraG homologs are widespread in Nature. Structural comparisons indicated that bacterial DraG is closely related to Archaea and mammalian ADP-ribosylhydrolases (ARH). In all available structures, the ARH active site consists of a hydrophilic cleft carrying a binuclear Mg(2+) or Mn(2+) cluster, which is critical for catalysis.
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